1. Field of the Invention
The present invention relates to diagnosis of inflammatory diarrhea, using a simple, convenient assay that requires minimal laboratory skills or experience.
2. Prior Art
A need exists for a simple, reliable in vitro test for fecal leukocytes (even after they are morphologically disrupted), to indicate that a subset of patients with the common problem of diarrhea that is inflammatory and thus requires specific, more costly diagnostic and therapeutic attention.
Diarrheal illnesses are extremely common (causing 2 to 12 or more illnesses per person per year) throughout the world, and often pose diagnostic and therapeutic questions for the physician. Fortunately, important diagnostic clues can be obtained by considering whether the diarrhea is a noninflammatory process arising typically from the upper small bowel, or whether it is an inflammatory diarrhea arising from an invasive process in the ileum or colon. Although the majority of cases are noninflammatory and will often respond to simple oral rehydration therapy, it is important to distinguish the invasive, inflammatory diarrheas, which are usually caused by Shioella, Salmonella, Campylobacter or Clostridium bacteria that may be more severe and should be the focus of more expensive culturing for these invasive pathogens. The invasive, inflammatory diarrheas may also require specific antibiotic treatment. A particularly helpful diagnostic clue to distinguishing inflammatory from noninflammatory diarrheas has been the examination for large numbers of leukocytes (white blood cells or "pus cells") in the diarrheal fecal specimens themselves. However, this requires that the physician or a skilled technician promptly examine mucus from a cup fecal specimen under a microscope, stained for clearly distinguishable leukocytes in the fecal debris. This requires the immediate availability of a skilled person with a microscope to stain and examine fresh fecal specimens in the clinic or emergency area where the patient is seen. Despite extensive efforts, this is difficult to accomplish, especially with this extremely common problem in a busy clinic setting.
There are many potential markers for leukocytes in the primary and secondary granules. Leukocyte esterase was explored as a potential marker for fecal leukocytes, since an analogous test exists for leukocytes in urine. However, it was discovered that leukocyte esterase was non-specifically positive for all stool samples, both those with and without leukocytes.